库车前陆冲断带“石英桥”的发现及地质意义  

Discovery of“Quartz Bridge”in Kuqa Foreland Thrust Belt and Its Geological Significance

作　　者：王钊 吕修祥[1] 张镭馨 李峰[1] 欧阳思琪 汪瑞 Wang Zhao;LüXiuxiang;Zhang Leixin;Li Feng;Ouyang Siqi;Wang Rui(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China;Consulting Center for Strategic Assessment,Academy of Military Science,Beijing 100097,China;China National Petroleum News,Beijing 100011,China)

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]军事科学院战略评估咨询中心,北京100097 [3]中国石油报社,北京100011

出　　处：《地球科学》2023年第1期342-358,共17页Earth Science

基　　金：国家油气重大专项(No.2017ZX05008003-010)。

摘　　要：在薄片和岩心等资料的基础上,利用扫描电镜、流体包裹体和离子探针微区原位同位素分析技术,在库车前陆冲断带克深-大北地区白垩系砂岩储层裂缝中首次发现了“石英桥”.石英桥是裂缝内高度局部化的孤立石英次生加大堆积体,离散分布于裂缝面,呈“桥”状跨越裂缝壁.石英桥内部发育多个近平行于裂缝壁的流体包裹体组,其均一温度范围(150~176℃)与石英骨架颗粒中流体包裹体均一温度范围(90~120℃)差异较大.此外,石英桥的氧同位素组成(平均δ^(18)O_(VSMOW)为17‰~21‰)与石英骨架颗粒和次生加大的氧同位素组成(平均δ^(18)O_(VSMOW)为8‰~17‰)亦差异较大.克深-大北地区石英桥主要发育在平行褶皱轴裂缝中,其形成可能与深埋高温环境下褶皱变形过程中的伸展作用以及古近系蒸发岩流体(富集18O)的运移有关.石英桥是一个兼具前沿性和实用性的研究领域,对于恢复裂缝张-闭历史和保存裂缝物性有重要的意义.Based on thin section and core data,quartz bridges in natural fractures of Cretaceous sandstones of the Keshen-Dabei area in the Kuqa foreland thrust belt were discovered by SEM,fluid inclusions and ion microprobe in-situ isotope.Quartz bridge is highly localized overgrowth accumulations that span fracture walls and is scattered on the fracture surface.Fluid inclusion assemblages sub-parallel to the fracture walls were observed in the quartz bridge.Their homogenization temperature range(150-176℃)is different from that of the fluid inclusions in quartz grains(90-120℃).Besides,the scope ofδ^(18)O_(VSMOW)values(17‰-21‰)does not overlap with that of quartz grain and quartz secondary enlargement(8‰-17‰).In the Cretaceous sandstone of the Keshen and Dabei area,quartz bridges are widespread in the hinge-parallel fractures.The formation of quartz bridge may be related to the extension during folding in the high-temperature at great depth and the migration of18O-enriched water of Paleogene evaporates.The research of the quartz bridge is a frontier and practical field,which has great significance for reconstructing fracture opening history and preserving fracture physical properties.

关 键 词：构造成岩作用 碎屑岩储层 天然裂缝 胶结物 石英桥 石油地质学 

分 类 号：P618.13[天文地球—矿床学]